How do X-ray measurements help us measure the amount of dark matter in galaxy clusters?
A) X-rays are emitted by hot gas, and the intracluster gas is heated by collisions with dark matter particles. More dark matter leads to greater heating, and hence stronger X-ray emission.
B) Dark matter absorbs X-rays. Therefore, more dark matter leads to weaker X-ray emission from galaxy clusters.
C) X-rays are emitted by hot gas, and the intracluster gas is heated by the gravitational effects of dark matter. More dark matter leads to greater heating, and hence stronger X-ray emission.
C
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Jupiter is noticeably oblate because:
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In the case of light waves, the thing doing the "waving" is
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In an analysis relating Bohr's theory to the de Broglie wavelength of electrons, when an electron moves from the n = 1 level to the n = 3 level, the circumference for its orbit becomes 9 times greater. This occurs because:
a. the wavelength of the electron becomes nine times as long. b. there are triple as many wavelengths, and each wavelength is triple in length. c. there are nine times as many wavelengths in the new orbit. d. the electron is moving nine times as fast.